You can use iptables to block connections, by example, using ufw the uncomplicated firewall:

# apt install ufw bind9-dnsutils  #  Install ufw and nslookup
# uIPs=$((nslookup reddit.com && \
  nslookup www.reddit.com && \
  nslookup redd.it && \
  nslookup redditstatic.com && \
  nslookup www.redditstatic.com) \
  | awk '/^Address: / { print $2 }' | sort -u); \
for uip in ${uIPs}; do \
  echo -n "${uip} " &&  \
  ufw deny from "${uip}" comment 'deny reddit.com'; \
  ufw deny out to "${uip}" from any comment 'deny reddit.com'; \
done;
# ufw enable
# ufw status numbered